I was thinking about that when I was dropping my 6 year old off at some hobbies earlier - it’s pretty much expected to have learned how to ride a bicycle before starting school, and it massively expands the area you can go to by yourself. When she went to school by bicycle she can easily make a detour via a shop to spend some pocket money before coming home, while by foot that’d be rather time consuming.
Quite a lot of friends from outside of Europe either can’t ride a bicycle, or were learning it as adult after moving here, though.
edit: the high number of replies mentioning “swimming” made me realize that I had that filed as a basic skill pretty much everybody has - probably due to swimming lessons being a mandatory part of school education here.
I couldn’t whistle until I had dental surgery and realized it moved my teeth so much I could finally whistle. So I was like 20 the first time I ever whistled.
Could whistle normally as long as I can remember. Tried forever to learn the two finger loud whistles as a kid and never could make a sound but still tried. I still recall when I was around 13 yo reading Goosebumps and randomly did the gesture when suddenly I made the first successfull attempt. I literally turned to the mirror on the side becuase of the surprise and had that Shaq face on Hot Ones. After practicing for a while I discovered that, while you can whistle EXTREMELY loudly this way, you legit hurt your own eardrums the most. Basically kamikaze whistling. I don’t use it that often because of it.
The third way of whsitling is by blowing through your palms which makes that owl-like howl. You can basically do the first part of the song in Once Upon a Time in the West this way.
Also, snapping your fingers in a very “snappy” loud and deep kinda way.
I could never do the two finger whistle and still can’t. Never tried whistling through my hands before.
But now that I’ve had multiple dental surgeries I have to be careful when I speak because sometimes I get the siblin s sound now as an adult and if I do it too hard it’s like a high pitched squeal.